Experiments in my laboratory are utilizing neurochemical and behavioral techniques to investigate how steroid hormones regulate and/or influence reproductive and non-reproductive behaviors in rats. Two areas are being investigated: the role the neurotransmitter serotonin (5-HT) in the hormonal regulation of female sexual behavior, lordosis, and the influence of steroid hormones on aging and memory function. Proposed experiments, utilizing primarily neurochemical techniques, will assess the activity of 5HT and related neurochemical during proestrus in specific hypothalamic sites which are known to regulate lordosis and where gonadal implemented to further assess serotonergic and monoaminergic function in hypothalamic sites after gonadal hormone administration, during the estrous cycle and after drug treatments. Whether GABA containing neurons in the hypothalamus serve as the mediators of gonadal hormone effects on serotonergic endings will be investigated. With advancing age most, but not all, humans, non-human primates and rats experience a diminishment in learning and memory function. Our experiments are assessing whether steroid hormones participate in or can influence this decline. Previous studies in the laboratory have shown that the gonadal hormone estradiol improves spatial memory function in young and aged rats. Current experiments are assessing whether estradiol dependent alterations in monoaminergic function contribute to this enhancement of function. Recent experiments have also shown that chronic stress, 21 days of restraint for 6 h/day, are associated with acquisition and performance impairments on the 8-arm radial maze. Chronic stress effects on spatial memory function will be further characterized and investigated, and monoamines measured in the hippocampus and other brain areas of the rats. The understanding of mechanisms of mechanisms for gonadal hormone regulation of brain function may be valuable for treatment of neuroendocrine problems such as infertility and spontaneous abortion in women, and psychosexual and impotency problems in men. Knowledge of serotonergic function within this neuroendocrine context may also provide information relevant for understanding how serotonergic systems exert effects on appetite, circadian rhythmicity, depression and anxiety states. Information concerning the effects of steroid hormones on learning and memory function may be valuable in treating age-related memory losses and provide information on possible contributions of chronic estradiol deficiencies and/or corticosteroid elevations in the etiology and management of Alzheimer's disease.